Model output discussion - 7th January onwards

[weirpig]

Central England   much of a muchness  loads to be resolved  quite a spread even at day 5 

 

Edited January 10, 2019 by weirpig

[bluearmy]

11 minutes ago, shaky said:

Control follows op with a bigger wedge at 192 hours!!could see upgrades this evening!!gfs 06z para loses the plot again and is different to the 00z run by quite a bit!

Again? The previous run was epic!  Unless you mean it isn’t following the previous run .  Anyway, no model can be said to ‘lose the plot’ in the transition period as we have no idea how that period will actually pan out ....

Edited January 10, 2019 by bluearmy

[Bruegelian]

But is it a certainty that a strong lobe of PV will end up over NE Canada? Surely it's too early to say for certain - Or maybe not? I'm not an expert.

[Ali1977]

11 minutes ago, northwestsnow said:

Tricky one, lots of factors to play with so height required will be known closer to the time..

I have had rain with uppers of -8 from the NW before now, the Irish sea is a real pain for this part of the country- i think i vowed never to entertain a north westerly again after one such disaster!!
Then again Jan 1984 produced big time here and that was a north westerly-

Will be interesting how this all unfolds, i'd say 300 m + and your for sure getting a dumping, GFS as i posted above is very snowy at times in FI - perhaps Exeter will continue to suggest hill snow for the north..

Looking at the GEFS I think Exeter won’t be deleting that line, especially with ECM and UKMO showing some good charts early on. 12z eagerly awaited. 

[swfc]

2 minutes ago, Matty88 said:

Nicely put, I'd say the predicted lobe of severe cold sliding into Canada/N America is definitely not a good factor (and never has been) in producing us a nice cold spell. Expect zonal cold 'snaps' until February and maybe beyond in my view - doesn't mean we won't see transient snow events though 

Yep good points.imo any sustained cold if it occurs will manifest itself with small rises in pressure threw Iceland towards the north east.nothing extreme ",more of a wedge type" put eventually a continental feed then easterly type weather.

[feb1991blizzard]

We just cannot seem to breach that -10c line with any quantity / frequency.

[shaky]

3 minutes ago, bluearmy said:

Again? The previous run was epic!  Unless you mean it isn’t following the previous run .  Anyway, no model can be said to ‘lose the plot’ in the transition period as we have no idea how that period will actually pan out ....

I think the wedge could upgraded this evening but your right with all sorts of stuff goin on high up who knows what the 12zs will show lol!!

[tight isobar]

Well the london ones indicative further for cold..

Check the drop and clustering!!!..

Pointing only 1 way!!!

Not brutal-but certainly notable..

And in the current situ...do we really expect any different atm..

Anyway...all on the correct page=colder-colder.

Edited January 10, 2019 by tight isobar

[bluearmy]

Just now, Bruegelian said:

But is it a certainty that a strong lobe of PV will end up over NE Canada? Surely it's too early to say for certain - Or maybe not? I'm not an expert.

 That’s what the modelling currently shows - and has done for a long time but without being a deep low thickness feature as is the current indication 

updated eps for London shows v cold and plenty of precip back end of the run 

[warrenb]

1 minute ago, Bruegelian said:

But is it a certainty that a strong lobe of PV will end up over NE Canada? Surely it's too early to say for certain - Or maybe not? I'm not an expert.

If the trop mirrors the strat then the lobe will go there, we basically have a 3 way split, but the two main lobes are over Eastern Europe (Hence the weather they are having) and over Canada (Hence the jet starting to fire up).

[northwestsnow]

1 minute ago, feb1991blizzard said:

We just cannot seem to breach that -10c line with any quantity / frequency.

Thats probably because the majority are WNW/NW ..

[Ali1977]

Just now, feb1991blizzard said:

We just cannot seem to breach that -10c line with any quantity / frequency.

Great chart though, a few warmer outliers dragging that mean up slightly I think. I wonder what this chart looked like a week before some of the other cold spells , like 2018 beast or 2010. The grouping looks pretty good.

[johnholmes]

13 minutes ago, shaky said:

Control follows op with a bigger wedge at 192 hours!!could see upgrades this evening!!gfs 06z para loses the plot again and is different to the 00z run by quite a bit!

What on earth do you expect at that time scale?

Honestly it is more scientific to check the same run, so 00 OR 06 from the last issue. That way you will pick up any trends at far out imes (192 etc) than watching each frame on each run.

I'm not having a go simply suggesting you try what I suggest to see if it does give a better picture of how the model is dealing with the situation. Compare it with how you do it at the moment, see how it compares. By 144h and less than the new data will begin to be a better guide on each run but not at 192 etc-honest.

[bluearmy]

2 minutes ago, feb1991blizzard said:

We just cannot seem to breach that -10c line with any quantity / frequency.

That’s down the the lack of HLB

with low heights and a Euro trough predicted, the uppers won’t need to be so low to deliver 

[northwestsnow]

1 minute ago, bluearmy said:

 That’s what the modelling currently shows - and has done for a long time but without being a deep low thickness feature as is the current indication 

updated eps for London shows v cold and plenty of precip back end of the run 

North Atlantic high/Scandy trough dropping south?

[Bruegelian]

9 minutes ago, warrenb said:

If the trop mirrors the strat then the lobe will go there, we basically have a 3 way split, but the two main lobes are over Eastern Europe (Hence the weather they are having) and over Canada (Hence the jet starting to fire up).

Hmmm that's a pity it's panned out like that.

Still, latest JMA looks good with strong GL HP. And CFS also. Makes you wonder how they're seeing it.

Edited January 10, 2019 by Bruegelian

[Glacier Point]

Yes, remember this trend in ensembles (all major modelling has this) is against what the models will be inclined to do the further one ventures.

FWIW, I'm seeing opportunity for +AAM tendency week 3, which would suggest impending further hemispheric amplification transposed onto a pattern that's already pretty amplified (Wave number 4).

Edited January 10, 2019 by Glacier Point

[johnholmes]

6 minutes ago, weirpig said:

Central England   much of a muchness  loads to be resolved  quite a spread even at day 5 

 

True but the overall trend, best shown at 500 mb is generally down. Less so at 850 mb and I am sure if you look at the surface even more so.

Why?

Because there is far more moisture to try and sort out for the computer and also much more topography issues the lower down one comes in the atmosphere.

[feb1991blizzard]

1 minute ago, bluearmy said:

That’s down the the lack of HLB

with low heights and a Euro trough predicted, the uppers won’t need to be so low to deliver 

True - and 45% on the snow row at that range is an absolute stonker, and you could also say the graph answers my other concern (will it be sustained or will milder sectors melt snow / deliever rail?)  and admittedly the fact that they are flatlining suggests now.

[swfc]

8 minutes ago, swfc said:

Yep good points.imo any  cold if it occurs will manifest itself with small rises in pressure threw Iceland towards the north east.nothing extreme ",more of a wedge type" put eventually a continental feed then easterly type weather.

There you go !!!!!

Edited January 10, 2019 by swfc

[WhiteFox]

8 minutes ago, tight isobar said:

Well the london ones indicative further for cold..

Check the drop and clustering!!!..

Pointing only 1 way!!!

A very good point which seems to keep getting lost....

The mean hovers around -5, but the largest clusters of runs are between -5 and -10 after roughly 19th January. There is a smaller cluster with much milder members which are skewing the mean upwards. I'd be pretty pleased with that set of ensembles if I were looking for cold!

Edited January 10, 2019 by WhiteFox
Sleep to keep....

[feb1991blizzard]

5 minutes ago, johnholmes said:

WBy 144h and less than the new data will begin to be a better guide on each run but not at 192 etc-honest.

TBH anything 192 or more i would use the ensemble suites tbh.

[weirpig]

Para on it again.  its like the gfs18z pub run but on steroids  constantly spewing out   day after tomorrow charts 

[Tim Bland]

A significan snow event is becoming a theme around the 22nd / 23rd 

[northwestsnow]

1 minute ago, weirpig said:

Para on it again.  its like the gfs18z pub run but on steroids  constantly spewing out   day after tomorrow charts 

Goodness me that is a STONKING chart..